It is known that it is desirable, in particular in the approaching and landing phases, to be able to estimate, aboard an aircraft, in particular a transport aircraft, the force and the direction of the wind, i.e., the speed and the moving direction, with respect to the ground, of the air mass in which the aircraft moves.
Such speed and wind direction information could be more particularly used:                for managing the aircraft navigation (flight plan); and        for assisting steering, in particular upon approaching a landing runway and the subsequent landing.        
Such a wind estimation is generally achieved through the aircraft speed with respect to the ground, being, for example, determined by means of on-board inertia units, and the aircraft speed in the air, being, for example, measured by means of pressure probes, also on board.
However, such a usual estimating method often leads to erroneous results, more particularly due to a possible mismatch between the results as obtained from two redundant ways generally provided on aircrafts. It is known, from FR-2 906 615, a wind estimating device which allows to perform, aboard an aircraft, an accurate estimation of the wind. To this end, such a usual device uses, in addition to the above mentioned speed information, a piece of information relating to the attack of the aircraft in the air, for calculating the horizontal component of the wind (force and direction). Taking into account the attack, i.e., the moving slope of the aircraft in the air, in addition to such a move speed, allows for a more accurate estimation of the wind to be reached. Such an estimation of the wind could be further refined through taking into account an additional piece of information being representative of the measured slide slip.
In such usual estimations, the speed of the wind is calculated from the difference between the ground speed of the aircraft and the speed of the aircraft in the air. Such a calculation is exact, when the measurements of the ground and air speeds are expressed in one single point of the aircraft. Now, this is not generally the case. In fact:                the ground speed of the aircraft is generally expressed (i.e. defined) at the centre (gravity centre or reference centre) of the aircraft; whereas        the air speed and the slide slip and attack angles are obtained from measurements achieved by common probes being generally located at the level of the front tip of the aircraft, where the air flow is the least turbulent.        
Consequently, due to the use of data as obtained from the measurements achieved at two different points of the aircraft, the usual estimations of the wind show some inaccuracy, as soon as the aircraft performs rotation operations. The usual estimations are thus only accurate when the aircraft is flying along a straight line. Such an important drawback restricts the cases of use for the wind speed estimated by the common devices.
Additionally, in the usual solutions, estimating in general occurs only in two dimensions in the horizontal plane, i.e. in the plane being normal to the surface of the earth. This also contributes to limit the cases of use for the estimated wind speed.